The present invention is concerned with the form of and a method of forming a bearing assembly particularly adapted for use where the bearing is subject to axial loads, in very compact machine assemblies without fastening tool access to the bearing housing and where robot machine assembly is desirable.
The present invention arose in addressing the problem of assembling a bearing into a compact vehicular gear box housing where the bearing is journaled onto a gear shaft of the gear box together with a number of other components such as gears. It will hereafter be described in that context but unless otherwise stated the invention may have applications in many other similar structures. In such a gear box the gear shaft is journaled onto a bearing and the bearing received into a bearing housing formed in the gear box casing. The fitting of the outer is typically an engineering interference fit or similar means of location such that the outer is not free to take up a different angular orientation. In operation the shaft is subject to axial forces which urge the bearing out of its housing in each axial direction. The forces directed axially out of the casing are resisted by a shoulder formed in the casing. However a retaining means must act between the outer race of the bearing and the casing to prevent axial displacement in the opposite direction. An example of conventional means may be a circlip received into a groove formed in the wall of the bearing housing. However, the installation of such retaining means requires access by a tool to the inside of the casing and is difficult to implement robotically. Further the use of circlips and like devices requires a loose fit between the bearing outer and the circlip which undesirably permits axial movement of the bearing and occupies space in the axial direction. Also, circlips and similar devices are not easy to disassemble without good tool access. If such access requirement can be obviated robot assembly will be possible and the bulk of the gear box can be reduced with numerous advantages which will be apparent to the skilled person.
Also known in the prior art is EP1265339 which discloses a bearing assembly in a motor. A retaining plate is first mounted temporarily onto a shaft. A bearing is then journaled onto the shaft. The assembled retaining plate and bearing are then inserted into the motor casing with the outer race of the bearing being inserted into a bearing housing. This presents a problem in that the retaining plate must be dismounted from the shaft before operation. Further the retaining plate cannot be arranged to sit flush with the inner end of the bearing so that the axial length of the bearing and housing assembly is not minimised.